Some wounds, such as pressure or diabetic ulcer wounds, or surgically created wounds, form a cavity in a patient's body. It may be desirable to fill the wound cavity, for example as part of a course of treatment. Various types of wound dressings or pads are used to fill wound cavities. These wound dressings or pads must be fitted for the particular wound size and shape, which can vary greatly. Some such dressings are easily conformable to the size and shape of the particular wound being treated. For example, gauze may be used as a cavity wound filler. As a further example, MELGISORB™ (produced by Molnlycke Health Care) is a soft, sterile calcium sodium alginate dressing that is used to fill wound cavities.
In some wound care applications, it may be desirable to use a wound pad made of a less conformable material. For example, porous and semi-rigid polymer foams are often used as wound fillers during negative pressure wound treatment. These materials may offer the advantage of allowing fluid channels through themselves even when subjected to negative pressure. Without wishing to be bound by any particular theory, it is also thought that the mechanical interaction between these more rigid materials and the wound may contribute to wound healing processes. The suitability of such less conformable materials notwithstanding, these dressings or pads can be difficult to size and shape to fit a wound. Such pads are typically supplied in one of several standard sizes and shapes, which then must be individually altered, typically with a utensil such as scissors.
A foam produced in situ in a wound cavity has particular advantages in the use as a wound filler as the produced foam can conform and adapt to a given shape of a wound cavity. Examples of foam material that can be used as in situ formed wound filler include polyurethane foam, and silicone foam such as Cavi-Care™. In such known foam materials, the foam is generally produced by mixing liquid components, e.g. pre-polymer, in the wound cavity, wherein the components react to cross-link, which reaction in turn releases the gas (e.g. carbon dioxide in case of a polyurethane foam and hydrogen gas in case of Cavi-Care™), which is required to form the foam cells.
One problem of these known foaming systems, which can also be described as “chemical foaming” systems, is that the foaming process is dependent on the reaction rate of the curing reaction (which reaction leads to the formation of the gas necessary to form the pore structure). Said reaction rate cannot be allowed to be too fast nor too slow, in order to achieve a desirable, e.g. open-cell, foam structure. Thus, it may be difficult to control the overall foaming process. Consequently, the foaming process is typically relatively slow, and it can thus be difficult to estimate how much material is required for a given wound cavity as the foam continues to form over several minute and may rise up over the edge of the wound cavity and spread out laterally onto the peri-wound area, long after a given amount of foam components was mixed in the cavity, which effects clearly are not desirable. Another problem with a relatively slow foaming process is that the unreacted (liquid) components may flow out from the cavity site, in particular in case the cavity is located on a difficult to dress area and/or on a vertical surface of the body.
WO 2012/001371 discloses a method and apparatus for providing a wound filler at a wound site prior to the application of negative pressure wound therapy, the method of WO'371 comprising: securing at least one drape element over a wound site, and subsequently injecting filler material through at least one opening in the drape. Thereby, the risk of excess foam on the peri-wound area, as discussed above, can be reduced. However, the solution provided in WO'371 is complicated and requires the use of drape which can be undesirable as such a drape, inter alia, limits the possibility of visual inspection and control of the cavity (which can often have complex 3D form) when filling it up with foam material. Also, excess foam material still may flow out from the opening in the drape.
Hence, there is a need in the art to provide a device for producing a foam having improved control of the foaming process and/or avoiding at least one of the disadvantages as discussed above.